Frost protection combined with on/off thermostat
When an on/off thermostat is used, the pipes and radiators in a frost-sen
sitive room can be protected by a frost thermostat. The radiator valve in
the frost-sensitive room must be open.
1. Place a frost thermostat (Tv) in a frost-sensitive room (e.g. a ga
rage).
2. Connect the frost thermostat (Tv) parallel to the on/off thermostat
(Tk) on the On/Off OT terminals of the connector.
Note
When an OpenTherm thermostat is used, it is not possible to con
nect a frost thermostat parallel to the On/Off OT terminals. In that
case, implement frost protection of the central heating system in
combination with an outside sensor.
Frost protection combined with outside sensor
The central heating system can also be protected against frost in combina
tion with an outside sensor. The radiator valve in the frost-sensitive room
must be open.
1. Connect the outside sensor to the Tout terminals of the connector.
The frost protection works as follows with an outside sensor:
At an outside temperature lower than -10°C (can be set with parameter
): the circulating pump switches on.
At an outside temperature higher than -10°C (can be set with parameter
): the circulating pump continues to run and then switches off.
Connecting an outside sensor
Ba Outside sensor
An outside sensor can be connected to the Tout terminals of the connector
(accessory). In the event of an on/off thermostat, the boiler will regulate
the temperature using the set point of the internal heating curve (F). Vari
ous parameter settings can be used to change the internal heating curve.
1. Connect the two-wire cable to the Tout terminals of the connector.
Note
An OpenTherm controller can also use this outside sensor. In that
case, the required internal heating curve must be set on the con
troller.
Setting the heating curve
1
2
3
4
F Heating curve
If an outside temperature sensor is connected, it is possible to adapt the
internal heating curve. The setting can be modified using parameters
,
,
and
.
Fig.22 Connecting the frost thermostat
AD-0000049-01
OT
On
/off
Tout
Tdhw
BL
RL
Tk
Tv
On/off
OT
BL
RL
Tout
Tdhw
Fig.23 Connecting an outside sensor
AD-0000048-01
Ba
OT
On
/off
Tout
Tdhw
BL
RL
On/off
OT
BL
RL
Tout
Tdhw
Fig.24 Heating curve
AD-3000038-01
0
10
20
-20
-10
10
30
70
50
90
F
1
3
4
2
6 Installation
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